Polymers based on fluoranthene and their use

ABSTRACT

Polymers comprising repeating units of the formula I  
                 
where the variables are defined as follows: a is an integer from 0 to 3, 
     R 1 , R 2 , R 3  are identical or different and are selected independently from among hydrogen, C 1 -C 20 -alkyl, C 1 -C 20 -alkyl containing one or more Si, N, P, O or S atoms, C 6 -C 30 -aryl, preferably C 6 -C 14 -aryl, C 4 -C 14 -heteroaryl, —N(C 6 -C 14 -aryl) 2 ,    and Y 1 , where Y 1  may be identical or different and are selected from among —CH═CH 2 , trans- or cis-CH═CH—C 6 H 5 , acryloyl, methacryloyl, methylstyryl, O—CH═CH 2  and glycidyl,  
                 
 
where Y 2  is selected from among —CH═CH 2 , trans- or cis-CH═CH—C 6 H 5 , acryloyl, methacryloyl, methylstyryl, —O—CH═CH 2  and glycidyl, and one or more groups Y 1  or Y 2  may be crosslinked to one another.

The present invention relates to polymers comprising repeating units ofthe formula I

where the variables are defined as follows:

-   a is an integer from 0 to 33,-   R¹, R², R³ are identical or different and are selected independently    from among hydrogen, C₁-C₂₀-alkyl, C₁-C₂₀-alkyl containing one or    more Si, N, P, O or S atoms, C₆-C₃₀-aryl, preferably C₆-C₁₄-aryl,    C₄-C₁₄-heteroaryl containing at least one S or N atom,    —N(C₆-C₁₄-aryl)₂,-   and Y¹, where Y¹ may be identical or different and are selected from    among —CH═CH₂, trans- or cis-CH═CH—C₆H₅, acryloyl, methacryloyl,    methylstyryl, O—CH═CH₂ and glycidyl,    where Y² is selected from among —CH═CH₂, trans- or cis-CH═CH—C₆H₅,    acryloyl, methacryloyl, methylstyryl, —O—CH═CH₂ and glycidyl, and    one or more groups Y¹ or Y² may be crosslinked to one another.

Electrically conductive polymers are of increasing economic andindustrial importance, for example in the field of electroluminescentdiodes. These can be used in a variety of ways, for example as displaysin mobile telephones or for visual display units in the computer sector.

Organic electroluminescent-diodes usually comprise a cathode and ananode which are separated by at least one film, more preferably at leasttwo films, of an organic material. The films typically have a thicknesswhich does not exceed 0.2 μm. The two electrodes are advantageously madeof different materials whose conduction band or valence band are closeto the potentials of the HOMO and LUMO energy levels of the polymersconcerned. At least one of the electrodes, either cathode or anode,comprises a metal film or a metal oxide film which has a thickness ofabout 0.2 μm and is optically transparent.

A review of organic electroluminescent diodes has been published by, forexample M. T. Bernius et al. in Adv. Mat. 2000, 12, 1737. The polymershave to meet demanding requirements and known materials are usually notable to meet all the demands made of them. It has been found that it isnot only the choice of monomers which is of great importance for theusability of the polymers.

Polymers based on fluoranthene and possibly other (co)monomers are knownper se. They are usually prepared by electrochemical coupling reactions,cf., for example, R. J. Waltman et al., J. Electrochem. Sci. 1985, 132,631. The formation of structurally very nonuniform polymers having ahigh polydispersity and low glass transition temperatures is observed.

U.S. Pat. No. 5,281,489 discloses the use of monomeric fluoranthene inorganic electroluminescent diodes. However, monomeric fluoranthene canmigrate under the conditions of use. The layer of monomeric fluorantheneis not stable, which results in a short life of the diodes.

U.S. Pat. No. 6,127,516 discloses electrochromic materials based on7,10-diphenylacenaphthofluoranthene, which can be produced by depositionon electrode surfaces. The molecular weight distribution is usually toobroad for use in diodes.

U.S. Pat. No. 5,777,070 discloses a process for preparing conjugatedpolymers which is based on the Suzuki coupling of monomers containinginternal groups, for example of the ethylene, acetylene, phenylene,fluorene, fluoranthene, anthracene, phenanthrene, etc., type and iscarried out in the presence of a phase transfer catalyst. The Suzukicoupling of monomers based on fluorene is described by way of example.However, the life of electroluminescent diodes comprising polyfluorenesis still in need of improvement.

WO 00/46321 discloses electrically conductive fluorene copolymerscomprising at least 10 mol % of 9-monosubstituted and/or9,9-disubstituted fluorene units.

It is an object of the present invention to provide novel electricallyconductive polymers which are suitable for use in diodes. A furtherobject is to provide a process for preparing the polymers of the presentinvention. Finally, it is also an object of the invention to provide newuses and application methods for the polymers of the present invention.

We have found that the first of these objects is achieved by thepolymers defined at the outset.

For the purposes of the present invention, the nomenclature offluoranthenes is according to the scheme below:

In the formula I, the variables are defined as follows.

-   a is an integer from 0 to 3, preferably 0 or 1 and very particularly    preferably 0.-   R¹, R², R³ are identical or different and are selected independently    from among hydrogen, C₁-C₂₀-alkyl such as methyl, ethyl, n-propyl,    isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl,    isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl,    n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl n-octyl, n-decyl,    n-dodecyl and n-octadecyl; preferably C₁-C₁₂-alkyl such as methyl,    ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,    tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl,    1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl, sec-hexyl and    n-decyl, particularly preferably C₁-C₄-alkyl such as methyl, ethyl,    n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl;-   C₁-C₂₀-alkyl containing one or more Si, N, P, O- or S-atoms, for    example —CH₂—CH₂—OCH₃, —[CH₂—CH₂]₂—OCH₃, —[CH₂—CH₂]₃—OCH₃,    —[CH₂—CH₂]₃—OC₂H₅, —[CH₂—CH₂]₃—O-n-C₃H₇, —[CH₂—CH₂]₃—O-i-C₃H₇,    —[CH₂—CH₂]₃-n-OC₄H₉, —CH₂—CH₂—SCH₃, —CH₂—CH₂—N(CH₃)₂,    —CH₂—CH—(OCH₃)₂, —CH₂—CH₂—P(CH₃)₂′—CH₂—CH₂—Si(CH₃)₃,    —CH₂—CH₂—OSi(CH₃)₃;-   C₆-C₃₀-aryl, for example phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl,    2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl,    4-phenanthryl and 9-phenanthryl, 9-fluorenyl or 2,8-indenofluorenyl,    preferably C₆-C₁₄-aryl, for example phenyl, 1-naphthyl, 2-naphthyl,    1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl,    3-phenanthryl, 4-phenanthryl and 9-phenanthryl, 9-fluorenyl,    particularly preferably phenyl, 1-naphthyl and 2-naphthyl,    particularly preferably phenyl;-   C₄-C₁₄-heteroaryl containing one or more S- or N-atoms, for example    N-pyrrolyl, pyrrol-2-yl, pyrrol-3-yl, N-imidazolyl, 2-imidazolyl,    4-imidazolyl, 1,2,4-triazol-3-yl, 1,2,4-triazol-4-yl, 2-pyridyl,    3-pyridyl, 4-pyridyl, 3-pyridazinyl, 4-pyridazinyl, 2-pyrimidinyl,    4-pyrimidinyl, 5-pyrimidinyl, N-indolyl and N-carbazolyl;-   —N(C₆-C₁₄-aryl)₂, where C₆-C₁₄-aryl may be identical or different    and are as defined above;    one or more groups Y¹, where Y¹ may be identical or different and    are selected from among —CH═CH₂, trans- or cis-CH═CH—C₆H₅, acryloyl,    methacryloyl, α-methylstyryl or para-methylstyryl, —O—CH═CH₂ and    glycidyl,    where Y² is selected from among acryloyl, methacryloyl,    α-methylstyryl or para-methylstyryl, O—CH═CH₂ and glycidyl, and one    or more groups Y¹ or Y² may be crosslinked to one another.

Preference is given to polymers comprising repeating units of theformula I a

where a is 0 or 1 and the other variables are as defined above. Veryparticular preference is given to a being 0 and R¹ and R² each beinghydrogen.

For the purposes of the present invention, the term polymers alsoencompasses compounds which have only 2 repeating units of the formula Ior I a and have a radical capping each end. Furthermore, the term“polymers” used in the context of the present invention also encompassescompounds which are made up of one repeating unit of the formula I or Ia and at least one comonomer unit which forms a conjugated system withthe repeating unit I or I a. Examples are para-phenylene units, trans-or cis-ethylene units, acetylene units, 1,4-naphthylene units,1,5-naphthylene units, 1,4-anthrylene units, 9,10-anthrylene units, alsoC₄-C₁₄-heteroarylene units containing N, S and/or 0 as heteroatoms, forexample 2,5-thiophene units, with the thiophene units preferably beingsubstituted in the 3 and 4 positions, 2,7-carbazolylene units,2,5-pyridylene units, where the comonomer units may also bear additionalsubstituents, for example cyano, C₁-C₆-alkoxy of di-C₁-C₆-alkylaminosubstituents. Further suitable comonomer units are

The polymers of the present invention comprise from 1 to 10 repeatingunits of the formula I or I a, preferably from 2 to 4, particularlypreferably from 2 to 3, repeating units of the formula I or I a. If thepolymers of the present invention have only 1 repeating unit of theformula I or I a, they have from 1 to 300 comonomer units, and if theyhave at least two repeating units of the formula I or I a, they havefrom 0 to 300, preferably up to 50, in particular up to 10, co-repeatingunits.

The polydispersity M_(w)/M_(n) of the polymers of the present inventionis preferably from 1.1 to 3.5.

The polymers are usually capped at the ends by a radical selected fromamong hydrogen, C₆-C₁₄-aryl and C₄-C₁₄-heteroaryl, with the radicalsbeing as defined above.

A further aspect of the present invention is a process for preparing thepolymers of the present invention. The polymers of the present inventionare preferably prepared by reactions of organometallic chemistry, forexample by Yamada coupling or by means of a Suzuki reaction. Preferenceis given to a process starting out from monomers of the formula II

and in particular of the formula II a,

where the variables are defined as follows:

-   X¹ and X² are identical or different and are selected from among    halogen, for example chlorine, bromine or iodine, in particular    chlorine or bromine, and esterified sulfonate such as    para-toluenesulfonate (tosylate), triflate (CF₃—SO₃—),    para-nitrophenylsulfonate (“nosylate”), para-bromosulfonate    (“brosylate”), in particular triflate; boron-containing radicals of    the formula —B(O—[C(R⁶)₂]n)—O), where-   R⁶ are identical or different and are selected from among hydrogen    and C₁-C₂₀-alkyl such as methyl, ethyl, n-propyl, isopropyl,    n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,    sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl,    isohexyl, sec-hexyl, n-heptyl, isoheptyl n-octyl, n-decyl, n-dodecyl    and n-octadecyl; preferably C₁-C₁₂-alkyl such as methyl, ethyl,    n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl,    n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl,    isoamyl, n-hexyl, isohexyl, sec-hexyl and n-decyl, particularly    preferably C₁-C₄-alkyl such as methyl, ethyl, n-propyl, isopropyl,    n-butyl, isobutyl, sec-butyl and tert-butyl, very particularly    preferably methyl;-   n is an integer from 2 to 10, preferably from 2 to 5.

Very particular preference is given to boron-containing radicals of theformula—B(O—[C(CH₃)₂]₂)—O).

Two alternative ways of carrying out the process of the presentinvention are, firstly, to use a monomer of the formula II in which X¹is selected from among halogen and esterified sulfonate and X² isselected from among boron-containing radicals and, secondly, to use atleast two different monomers of the formula II of which one monomer hastwo halogen atoms or two esterified sulfonate groups or one halogen atomand one esterified sulfonate group and the other monomer has twoboron-containing radicals —B(O—[C(R⁶)₂]n)—O). In the latter case, itneeds to be ensured that the molar ratio of the sum of halogen andesterified sulfonate to boron-containing radicals is from 0.8:1 to1.2:1.

The polymerization is preferably carried out in the presence of a nickelor palladium compound in which the metal is particularly preferably inthe oxidation state 0. Very particular preference is given to thecommercially available tetrakis(triphenylphosphine)palladium[Pd{P(C₆H₅)₃}₄] and also commercially available nickel compounds, forexample Ni(C₂H₄)₃, Ni(1,5-cyclooctadiene)₂ “Ni(COD)₂”,Ni(1,6-cyclodecadiene)₂, or Ni(1,5,9-all-trans-cyclododecatriene)₂.Particular preference is given to Ni[COD]₂. To carry out thepolymerization, an excess of P(C₆H₅)₃ or 1,5-cyclooctadiene can beadded. When the polymerization is carried out in the presence ofpalladium compounds, it is usually sufficient to use catalytic amounts,i.e. from 0.1 to 10 mol % of Pd, based on monomer of the formula II orII a. If the polymerization is to be carried out in the presence ofnickel compounds, stochiometric amounts of Ni, based on the sum ofmonomers of the formula II or II a and any comonomer, are usuallyrequired.

The polymerization is usually carried out in an organic solvent, forexample toluene, ethylbenzene, meta-xylene, ortho-xylene,dimethylformamide DMF, tetrahydrofuran, dioxane or mixtures of these.The solvent or solvents is/are freed of traces of moisture by methodscustomary in the laboratory prior to the polymerization. Thepolymerization is usually carried out under protective gas; suitableprotective gases are nitrogen and noble gases, in particular argon, andCO₂.

The polymerization is usually carried out in the presence of a base, forexample an organic amine. Triethylamine, pyridine and collidine areparticularly useful.

The polymerization can also be carried out in the presence of solidbasic salts, for example alkali metal carbonate or alkali metalbicarbonate, in the presence or absence of a crown ether such as18-crown 6. It is also possible to carry out the polymerization as atwo-phase reaction using aqueous solutions of alkali metal carbonate, inthe presence or absence of a phase transfer catalyst. In this case, itis not necessary to free the organic solvent of moisture prior to thereaction.

The polymerization usually takes from 10 minutes to 2 days, preferablyfrom 2 hours to 24 hours. The pressure conditions are not critical, andpreference is given to atmospheric pressure. The polymerization isusually carried out at elevated temperature, generally from 80° C. tothe boiling point of the organic solvent or solvent mixture, inparticular from 100° C. to the boiling point of the organic solvent orsolvent mixture.

If copolymers of monomers of the formula II and the above-describedcomonomers are to be prepared, the comonomers used are the appropriatepara-phenylene compounds, trans- or cis-ethylene compounds, acetylenecompounds, 1,4-naphthylene compounds, 1,5-naphthylene compounds,1,4-anthrylene compounds, 9,10-anthrylene compounds and/or 2,5-thiophenecompounds which bear the abovementioned radicals X¹ and X², with theabovementioned proviso regarding the molar ratios of halogen andesterified sulfonate to boron-containing radicals.

A further aspect of the present invention is monomers of the formulaIII,

in particular of the formula III a

where the variables are as defined above. Monomers of the formula IIIand in particular of the formula III a are used for preparing thepolymers of the present invention. A further aspect of the presentinvention is a process for preparing the novel monomers of the formulaIII and in particular III a. The process of the present invention startsout from compounds of the formula IV or IV a,

where X³ and X⁴ are each halogen, in particular chlorine or bromine, oresterified sulfonate, in particular triflate (CF₃—SO₃—).

To carry out the process of the present invention, the compounds of theformula IV and in particular of the formula IV a are firstly singly ordoubly metalated by means of at least two or at least four equivalentsof a strong organometallic base and the products are subsequentlyreacted with one or two equivalents of a boron compound of the formula V

where the variables R⁶ and n are as defined above and X⁵ is selectedfrom among C₁-C₆-alkoxy such as methoxy, ethoxy, h-propoxy, isopropoxy,n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy,n-hexoxy and isohexoxy, particularly preferably methoxy, ethoxy,n-propoxy, isopropoxy and n-butoxy. X⁵ is very particularly preferablyisopropoxy.

Bases which can be used are the metal alkyls customary in organometallicchemistry, for example methyllithium, ethyllithium, n-butyllithium,sec-butyllithium, tert-butyllithium or hexyllithium, also Grignardcompounds such as ethylmagnesium bromide. Solvents which have been foundto be useful are high-boiling solvents such as toluene, ortho-xylene,meta-xylene, para-xylene, ethylbenzene or mixtures of these, alsononcyclic or cyclic ethers such as 1,2-dimethoxyethane, tetrahydrofuran,dioxane or diethyl ether.

The metalation is generally complete after a few hours; a reaction timeof from 1 to 10 hours is appropriate and preference is given to from 2to 5 hours. The temperature conditions are generally not critical, andcarrying out the reaction at from −90° C. to −20° C. has been found tobe preferred.

The singly or doubly metalated compound of the formula IV or IV a issubsequently reacted with at least one or two equivalents of a boroncompound of the formula V. For this purpose, the two components aremixed with one another in a suitable solvent such as benzene, toluene,ethylbenzene, orthoxylene, meta-xylene or para-xylene, chlorobenzene,cyclohexane, acetonitrile, tetrahydrofuran, 1,2-dimethoxyethane, dioxaneor diethyl ether or a mixture thereof. The reaction can be carried outat from −100° C. to +150° C., preferably from −78° C. to +100° C. It isimportant that the reaction is carried out in the absence of oxygen andmoisture.

The pressure conditions are generally not critical, and preference isgiven to atmospheric pressure. The preferred reaction time is from 10minutes to 2 days, more preferably from 1 hour to 24 hours.

The work-up and purification of the novel monomers of the formula III orIII a can be carried out by conventional methods, for exampleextraction, permeation, crystallization, chromatography, precipitationor sublimation.

Boron compounds of the formula V can be synthesized readily, and somederivatives are commercially available from Sigma-Aldrich.

The compounds of the formula IV or IV a can be obtained fromfluoranthene or the appropriate fluoranthene derivatives by reactions orreaction sequences which are known in principle. The preparation of thevery particularly preferred compounds IV a.1 and IV a.2

is carried out, for example, by chlorination or bromination ofunsubstituted fluoranthene in, for example, glacial acetic acid ornitrobenzene using two equivalents of Cl₂ or Br₂. The preparation of thevery particularly preferred compounds IV a.3 and IV a.4

can be carried out, for example, by dinitration of fluoranthene,subsequent reduction of the nitro groups to amino groups, diazotizationof the amino groups using NaNO₂/HCl or amyl nitrite and thermaldecomposition of the diazonium salts and subsequent reaction of thephenolic OH groups with CF₃SO₂Cl to form the bis-triflate IV a.3 or withpara-CH₃—C₆H₄—SO₂Cl to form the bis-tosylate IV a.4.

A further aspect of the present invention is a further process forpreparing the polymers of the present invention.

In this process, preference is given to photochemically or thermallypolymerizing monomers of the formula VI

where at least one, preferably two, of the radicals R¹ to R³ is/areselected from Y¹, where Y¹ are identical or different and are selectedfrom among —CH═CH₂, trans- or cis-CH═CH—C₆H₅, acryloyl, methacryloyl,α-methylstyryl and para-methylstyryl, —O—CH═CH₂ and glycidyl,

where Y² is selected from among acryloyl, methacryloyl, α-methylstyryland para-methylstyryl, —O—CH═CH₂ and glycidyl, and the other radicalsare as defined above, with one another.

Preference is given to thermally or photochemically polymerizing orcopolymerizing monomers of the formula VI a

with one another.

A thermal polymerization or copolymerization is preferably carried outby applying monomers of the formula VI or VI a in which at least one,preferably two, of the radicals R¹ to R³ are selected from among readilythermally polymerizable radicals Y¹ which may be identical or differentand are selected from among trans- or cis-CH═CH—C₆H₅, α-methylstyryl andpara-methylstyryl,

where Y² is trans- or cis-CH═CH—C₆H₅, α-methylstyryl orpara-methylstyryl, as such or as a solution, if appropriate togetherwith comonomers, as a film, preferably on one of the electrodes, andheating this film for from 10 minutes to 1 hour under nitrogen or noblegas. A temperature range from 40 to 120° C. has been found to be useful.Any comonomers present likewise have to bear at least one, preferablytwo, of the above-described readily thermally polymerizable radicals Y¹per molecule.

A photochemical polymerization or copolymerization is preferably carriedout by applying monomers of the formula VI or VI a in which at leastone, preferably two, of the radicals R¹ to R³ is/are selected from amongreadily photochemically polymerizable radicals Y¹ which may be identicalor different and are selected from among acryloyl, methacryloyl,—O—CH═CH₂ and glycidyl and

where Y² is selected from among acryloyl, methacryloyl, —O—CH═CH₂ andglycidyl, as such or as a solution, if appropriate together withcomonomers, as a film preferably on one of the electrodes, andilluminating this film with a radiation source, for example a UV lamp,in the presence of a customary photoinitiator known from thephotopolymerization of, for example, acrylic acid derivatives ormethacrylic acid derivatives or unsaturated ethers. Any comonomerspresent likewise have to bear at least one, preferably two, of theabove-described readily photochemically polymerizable radicals Y¹ permolecule.

The monomers of the formula VI or VI a can be prepared from, forexample, compounds of the formula IV, in particular IV a.1 to IV a.4, byreactions known in principle, for example the Hecke reaction or theStille coupling.

The polymers of the present invention can comprise units of the formulaVII, preferably VII a,

where a′ is an integer from 0 to 2, preferably from 0 to 1 andparticularly preferably 0, and the other variables are as defined above.Polymers comprising monomer units of the formula VII or VII a can besynthesized by addition of, for example, monomers of the formula VIIIa-d

during the palladium- or nickel-catalyzed polymerization of the monomersof the formula II or II a.

Further aspects of the present invention are the use of the novelpolymers comprising repeating units of the formula I or I a forproducing organic electroluminescent diodes and also organicelectroluminescent diodes produced using the polymers of the presentinvention. The organic electroluminescent diodes of the presentinvention comprise at least one organic film, advantageously at leasttwo organic films, of which at least one has electroluminescentproperties and comprises an electroluminescent polymer according to thepresent invention. The organic electroluminescent diodes of the presentinvention further comprise a cathode and an anode which are separated byat least one film, more preferably at least two films. The filmsadvantageously have a thickness which does not exceed 0.1 μm. The twoelectrodes are advantageously made up of different materials whoseconduction band or valence band is close to the potentials of the HOMOand LUMO energy levels of the polymers of the present invention. Atleast one of the electrodes, either cathode or anode, comprises a metalfilm or a metal oxide film which has a thickness of about 0.2 am. Theelectroluminescent diodes of the present invention can be produced, forexample, by applying a film comprising or consisting of the polymers ofthe present invention having a thickness of from 0.02 to 0.2 μm betweena cathode and an anode. Another method is to apply one or more films ofwhich at least one consists of a polymer comprising one or more polymersaccording to the present invention to an electrode and subsequently toattach the second electrode. One of the electrodes is opticallytransparent.

If an electric field or an electric potential is then applied, electronsare injected into the lowest unoccupied energy level (LUMO) or holes areinjected into the highest occupied energy level (HOMO) of the polymer ofthe present invention and light emission occurs by recombination of thecharge carriers.

The application of the polymers of the present invention is usuallycarried out from a solution in an organic solvent such as an ether, achlorinated hydrocarbon such as methylene chloride or an aromatichydrocarbon such as toluene. The application itself can be carried outby conventional techniques, for example film-forming coating (screenprinting technique), by application using an ink jet printer, by stampprinting, for example by PDMS, namely stamp printing by means of asilicone rubber stamp which has been photochemically structured.

The electroluminescent films of the present invention which comprisepolymers of the present invention or consist of these usually have athickness of from 0.01 to 0.4 μm, preferably from 0.05 to 0.2 μm. Theycan further comprise other constituents which are generally customary inproduction of organic electroluminescent diodes. The films of thepresent invention can be used for producing organic electroluminescentdiodes; compared to electroluminescent diodes known from the prior art,these have a longer life and further advantageous properties.

The invention is illustrated by the examples.Synthesis of Compound III a.1

8 g of 3,8-dibromofluoranthene IV a.2, prepared by dibromination offluoranthene in nitrobenzene, were dissolved in 90 ml of THF underprotective gas and cooled to −5° C. 61 ml of tert-butyllithium solution(15% strength by weight in pentane) were added dropwise and the mixturewas stirred at room temperature for 1.5 hours. 9.5 ml of2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane were added dropwiseat such a rate that the temperature did not exceed 5-20° C. The reactionmixture was stirred at room temperature for a further 15 hours. Thereaction mixture was poured into water and extracted a number of times(at least 3 times) with diethyl ether, the ether phase was dried overMgSO₄, concentrated by evaporation and purified by chromatography onsilica gel (Merck silica gel 60). Nonpolar impurities were eluted withcyclohexane, and the product was subsequently eluted with ethylacetate/cyclohexane (volume ratio=1:9). Yield: 50% as a yellow solid.The structure was confirmed by ¹H-NMR spectroscopy.

POLYMERIZATION EXAMPLE

1.56 mmol of 3,8-dibromofluoranthene IV a.2, 1.58 mmol of dipinacolylfluoranthene-3,8-diboronate (Compound III a.1), 0.011 mmol of phasetransfer catalyst Aliquate 336, commercially available from Aldrich, and2.5 ml of 2 molar aqueous sodium carbonate solution were mixed with 14ml of toluene and degassed by means of nitrogen. 1.33 ml of a 0.1%strength by weight solution of tetrakis(triphenylphosphine)palladium intoluene were added. The mixture was maintained at 90-100° C. for 48hours under argon. Finally, 0.82 ml of a 1% strength by weight solutionof bromobenzene in toluene was added and the mixture was stirred at thesame temperature for a further 24 hours.

For the work-up, the reaction solution was added dropwise to 50 ml of adilute methanolic HCl solution. The solid which precipitated wasfiltered off, purified over silica gel (Merck silica gel 60,eluant:toluene) and precipitated in methanol. The precipitation/silicagel purification procedure was repeated another three times. The productwas obtained as a yellowish powder.

1-9. (canceled)
 10. A monomer of the formula III

wherein the variables are defined as follows: a is an integer from 0 to3, R¹, R², R³ are identical or different and are selected independentlyfrom the group consisting of hydrogen, C₁-C₂₀-alkyl, C₁-C₂₀-alkylcontaining one or more Si, N, P, O or S atoms, C₆-C₃₀-aryl,C₄-C₁₄-heteroaryl containing at least one S or N atom, —N(C₆-C₁₄-aryl)₂,and Y¹, wherein Y¹ may be identical or different and are selected fromthe group consisting of —CH═CH₂, trans-CH═CH—C₆H₅, cis-CH═CH—C₆H₅,acryloyl, methacryloyl, methylstyryl, —O—CH═CH₂, glycidyl,

wherein Y² is selected from the group consisting of —CH═CH₂,trans-CH═CH—C₆H₅ cis-CH═CH—C₆H₅, acryloyl, methacryloyl, methylstyryl,—O—CH═CH₂ and glycidyl, and one or more groups Y¹ or Y² may becrosslinked to one another, R⁶ are identical or different and are each,depending on one another, hydrogen or C₁-C₂₀-alkyl, X¹ is selected fromthe group consisting of halogen, esterified sulfonate andboron-containing radicals of the formula —B(O—[C(R⁶)₂]n)—O), wherein R⁶is as defined above, and wherein n is an integer from 2 to
 10. 11. Amonomer of the formula III a

wherein the variables are defined as follows: a is an integer from 0 to3, R¹, R², R³ are identical or different and are selected independentlyfrom the group consisting of hydrogen, C₁-C₂₀-alkyl, C₁-C₂₀-alkylcontaining one or more Si, N, P, O or S atoms, C₆-C₃₀-aryl,C₄-C₁₄-heteroaryl containing at least one S or N atom, —N(C₆-C₁₄-arly)₂,and Y¹, wherein Y¹ may be identical or different and are selected fromthe group consisting of —CH═CH₂, trans-CH═CH—C₆H₅, cis-CH═CH—C₆H₅,acryloyl, methacryloyl, methylstyryl, —O—CH═CH₂, glycidyl,

wherein Y² is selected from the group consisting of —CH═CH₂,trans-CH═CH—C₆H₅, cis-CH═CH—C₆H₅, acryloyl, methacryloyl, methylstyryl,—O—CH═CH₂ and glycidyl, and one or more groups Y¹ or Y² may becrosslinked to one another, R⁶ are identical or different and are each,depending on one another, hydrogen or C₁-C₂₀-alkyl, X¹ is selected fromthe group consisting of halogen, esterified sulfonate andboron-containing radicals of the formula —B(O—[C(R⁶)₂]_(n))—O), whereinR⁶ is as defined above, and wherein n is an integer from 2 to
 10. 12. Aprocess for preparing monomers of the formula III, comprising:metalating compounds of the formula IV,

wherein X³ and X⁴ are identical or different and are selected from thegroup consisting of halogen and sulfonate, using at least two or atleast four equivalents of a strong organometallic base, to obtain aproduct, and subsequently reacting the product with one or twoequivalents of a boron compound of the formula V

wherein X⁵ is selected from from the group consisting of C₁-C₆-alkoxy,to obtain said compound of formula III

wherein the variables are defined as follows: a is an integer from 0 to3, R¹, R², R³ are identical or different and are selected independentlyfrom the group consisting of hydrogen, C₁-C₂₀-alkyl, C₁-C₂₀-alkylcontaining one or more Si, N, P, O or S atoms, C₆-C₃₀-aryl,C₄-C₁₄-heteroaryl containing at least one S or N atom, —N(C₆-C₁₄-aryl)₂,and Y¹, wherein Y¹ may be identical or different and are selected fromthe group consisting of —CH═CH₂, trans-CH═CH—C₆H₅, cis-CH═CH—C₆H₅,acryloyl, methacryloyl, methylstyryl, —O—CH═CH₂, glycidyl,

wherein Y² is selected from the group consisting of —CH═CH₂,trans-CH═CH—C₆H₅, cis-CH═CH—C₆H₅, acryloyl, methacryloyl, methylstyryl,—O—CH═CH₂ and glycidyl, and one or more groups Y¹ or Y² may becrosslinked to one another, R⁶ are identical or different and are each,depending on one another, hydrogen or C₁-C₂₀-alkyl, X¹ is selected fromthe group consisting of halogen, esterified sulfonate andboron-containing radicals of the formula —B(O—[C(R⁶)₂]_(n))—O), whereinR⁶ is as defined above, and wherein n is an integer from 2 to
 10. 13. Aprocess as claimed in claim 12, wherein compounds of the formula IV a

are used. 14-18. (canceled)
 19. The process according to claim 12,wherein X⁵ in formula V is isopropoxy.
 20. The process according toclaim 12, wherein X³ and X⁴ are each triflate.
 21. The process accordingto claim 12, wherein said base is a methyl alkyl.
 22. The processaccording to claim 12, wherein said metalation proceeds for 1 to 10hours.
 23. The process according to claim 12, wherein a reactiontemperature during metalation is −90° to −20° C.
 24. The processaccording to claim 12, wherein a reaction temperature during reactionwith said boron compound is −100° to +150° C.
 25. The process accordingto claim 12, wherein said reaction with said boron compound is carriedout in the absence of oxygen and moisture.
 26. The process according toclaim 12, wherein said reaction with said boron compound proceeds for 10minutes to 2 days.